12V battery maintenance for dummies when gone for weeks

I realize you are trying to be helpful but what explains 1 replacement battery in 10 years on my gen4 Prius using it in a rotation with my other 2 vehicles?

 

I know how the Gen 4/Gen 5 Prius BMS works, as I studied it with a battery monitor. You don't know the current SOC of your battery. At least, get a BM2 battery monitor and find out. I bet it is below 50%. Just because you have escaped so far from a dead battery doesn’t mean it will never happen.

Other battery maintainers might work. I hope what you have is a smart battery maintainer and not a dumb trickle charger as you think, since the latter can damage the battery.

 

I have 3 of those, lol. 1.25 amp model. I think they're good. They might be the original 'battery maintainer', not sure. Gotta be careful about throwing the term 'trickle charger' in these parts, lol.

 

Just out of curiosity where do you attach the battery maintainer? The battery itself or under the hood at the jump terminals?

 

I put a NOCO permanently next to the battery, under the cover. I haven't used it yet. I got one suitable for under hood mounting in case I went that way.

 

Also, attach a BM2 battery monitor to the battery.

BM2 battery monitor

 

meh, from the Amazon review summary:

Customers find that the QUICKLYNKS BM2 battery monitor works reliably and effectively monitors battery voltage. They appreciate that it's simple to install and offers good value for money. Opinions are split regarding battery charge monitoring - while some customers can track charge levels, others report that it drains the battery. Similarly, customers have mixed experiences with connectivity - some report immediate connection with the app, while others say it doesn't connect at all. The Bluetooth feature receives mixed feedback: some customers find it great, while others note its limited range

 

garbage in, garbage out

 

Too, I just don't fee a need for a constantly attached battery monitor, I have multimeter and electronic load tester I use occasionally. These onboard testers impose a constant background load?

 

tiny

 

Link

1.5 mA per link above. Didn't measure it.

 

Assume you've got it? You could test the manufacturer's claimed draw, putting a multimeter (in milliamperes mode) in series between neg battery post and ground, with/without it connected

 

I’ll pass